Oled display and touch screen

ABSTRACT

An OLED display and touch screen system includes a substrate; an OLED display including an array of individually addressable OLEDs formed on the substrate; and a touch screen including an OLED light emitter formed on the substrate the OLED light emitter defining an optical cavity for reducing the angle of emission of light from the OLED light emitter and a light sensor formed on the substrate across the display from the OLED light emitter, and optics located around the display above the OLED light emitter and the light sensor for directing light emitted from the OLED light emitter across the display to the light sensor.

[0001] This is a continuation-in-part of application U.S. Ser. No.10/346,987 filed Jan. 17, 2003.

FIELD OF THE INVENTION

[0002] This invention relates generally to organic light emitting diode(OLED) displays and, more particularly, to an OLED display with a touchscreen.

BACKGROUND OF THE INVENTION

[0003] Modem electronic devices provide an increasing amount offunctionality with a decreasing size. By continually integrating moreand more capabilities within electronic devices, costs are reduced andreliability increased. Touch screens are frequently used in combinationwith conventional soft displays such as cathode ray tubes (CRTs), liquidcrystal displays (LCDs), plasma displays and electroluminescentdisplays. The touch screens are manufactured as separate devices andmechanically mated to the viewing surfaces of the displays.

[0004] US 2002/0175900 A1 by Armstrong, published Nov. 28, 2002,describes a touch system for use with an information display systemincluding a frame defining an opening corresponding in size and shape toan information display area of a display. On each side is positioned anarray of light emitting devices with a light-transmissive prismpositioned along each array of light emitting devices such that lightemitted from the light emitting devices is directed across the touchinput area. The system also includes light detection devices positionedat each corner of the frame. In a preferred embodiment, the lightemitting devices are organic light emitting diodes.

[0005] When such a touch screen is used with a flat panel display, thetouch screen is simply placed over the flat panel display and the twoare held together by a mechanical mounting means such as an enclosure.These prior art arrangements combining touch screens and OLED displayssuffer from a variety of drawbacks. The use of frames increases theparts count, weight, and cost of the device. The separation between thetouch screen and display increases thickness. Redundant components foundin the display and touch screen further increase cost and decreaseperformance as compared to more integrated solutions. Moreover, the needfor separate cabling for the touch screen increases manufacturing costs

[0006] Thus, there remains a need for an improved touch screen, flatpanel display system that minimizes device weight, removes redundantmaterials, decreases cost, eliminates special mechanical mountingdesigns, increases reliability, and minimizes the degradation in imagequality.

SUMMARY OF THE INVENTION

[0007] The need is met according to the present invention by providingan OLED display and touch screen system that includes a substrate; anOLED display including an array of individually addressable OLEDs formedon the substrate; and a touch screen including an OLED light emitterformed on the substrate the OLED light emitter defining an opticalcavity for reducing the angle of emission of light from the OLED lightemitter and a light sensor formed on the substrate across the displayfrom the OLED light emitter, and optics located around the display abovethe OLED light emitter and the light sensor for directing light emittedfrom the OLED light emitter across the display to the light sensor.

ADVANTAGES

[0008] The display according to the present invention is advantageous inthat it provides a thin, light, easily manufacturable display havingreduced weight, size, and cost and a greater reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a schematic side view showing the basic structure of anintegrated OLED display and touch screen according to the presentinvention;

[0010]FIG. 2 is a schematic top view of the integrated OLED display andtouch screen;

[0011]FIGS. 3a, b, and c are schematic top views of an integrated OLEDdisplay and touch screen showing alternate locations of the emitters andsensors;

[0012]FIG. 4 is a schematic side view of an integrated OLED display andtouch screen wherein the optics located around the frame are mirroredsurfaces of the frame according to one embodiment of the invention;

[0013]FIG. 5 is a schematic side view of an integrated OLED display andtouch screen wherein the optics located around the frame are lightpipes; and

[0014]FIG. 6 is a schematic side view of an integrated OLED display andtouch screen wherein the OLED display is a bottom emitting display.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Referring to FIG. 1, a top-emitting OLED display device with anintegrated optical touch screen according to one embodiment of thepresent invention includes a rectangular substrate 42 with anencapsulating cover 44. Located on the substrate is an OLED display 60including electrodes and multiple layers of materials such ashole-injection layers and electron transport layers as is well known inthe art (not shown). Light 49 emitted from the display passes throughthe encapsulating cover 44 or is reflected from the substrate 42 and isemitted through the encapsulating cover 44. At one side of therectangular substrate 42 is an array of infrared OLED light emitters 62.Infrared OLED light emitters are known and can be made, for example, bydoping OLED devices with rare-earth ions such as neodymium or erbium. Atthe opposite side of the rectangular substrate 42 is an array ofinfrared light sensors 64. The sensors may include filters to improvetheir frequency response.

[0016] As shown in FIG. 2, a second pair of emitter and sensor arraysare arranged on the other two sides of the rectangular substrate 42.According to the present invention, both the light emitters 62 andsensors 64 are integrated on the same substrate as the OLED display 60.Optics, such as mirrors 66 are arranged over the encapsulating cover 44directly above the emitter and sensor arrays for directing light emittedfrom the light emitters 62 across the display to the light sensors 64.The mirrors 66 can be constructed using glass or plastic prisms with areflective side arranged at approximately 45 degrees to the cover 44.Alternatively, the mirrors can be supported at approximately 45 degreeangles with respect to the cover 44. A touch screen controller (notshown) is connected to the touch screen to operate the emitters 62 andsensors 64.

[0017] Referring to FIGS. 3a, b and c, a top view of alternativearrangements of the light emitters 62 and sensors 64 are shown. In thearrangement shown in FIG. 3a, the light emitters 62 are located in twoarrays adjacent two contiguous edges of the display 60 and the sensors64 are located in two arrays adjacent the other two edges of the display60. In the arrangement shown in FIG. 3b, the light emitters 62 andsensors 64 are interdigitated in arrays surrounding the display 60. Inthe arrangement shown in FIG. 3c, emitter arrays are located on all foursides of the display area 60 and sensors 64 are located at the cornersof the display 60, similar to the arrangement shown by Armstrong inpublished US Patent Application 2002/0175900.

[0018] In operation, the infrared OLED light emitters 62 emit light inevery direction. The light is reflected from the 45 degree mirrors 66located above the emitters and pass over the surface of the OLED display60. After passing over the surface of the OLED display, the light isreflected by the 45 degree mirrors located above the sensors 64 to theinfrared sensors 64. The sensors 64 detect the light and producefeedback signals that are supplied to the touch screen controller andinterpreted in a conventional manner to locate the position of an objectthat interrupts the light from the emitters 62. Because the touch screenelements are integrated on a common substrate with the display, a singleconnector may be used for both the touch screen and the display.Elements of the touch screen controller and/or the display controllermay be integrated on the substrate.

[0019] Because each infrared OLED light emitter 62 emits light in everydirection, a single emitter can be used in conjunction with multiplesensors 64 to detect a touch. Alternatively, multiple emitters can beused in conjunction with a single sensor to detect a touch. The emittersand sensors can be energized sequentially or in common to optimize theperformance of the touch screen under a wide variety of conditions,including high ambient light, low-power operation, a noisy environment,or high performance mode.

[0020] Because OLED light emitting elements emit light equally in everydirection, not all of which will strike the 45 degree mirrors, theperformance of the present invention can be enhanced by increasing theamount of light that is emitted orthogonally to the substrate so that agreater percentage of the light will reflect from the mirrors. Inconventional practice, up to 80% of the light emitted is lost because itis not transmitted through the cover or substrate of the display.Instead the light may be emitted in a direction parallel to thesubstrate and will waveguide through the light emissive layers.Therefore, reducing the amount of light emitted parallel to thesubstrate that propagates through the light emissive layers of organicmaterials by waveguiding action will increase the amount of light thatis emitted usefully toward the mirrors.

[0021] A reduced angle of emission from the OLED light emitting elementscan be achieved by forming an optical cavity between the electrodesproviding current to the OLED light emitting elements. Electrodes can bemade of highly reflective, thin layers of metal. By making the electrodeopposite to the direction of emission completely reflective and theelectrode though which light passes partially reflective, an opticalcavity can be formed. The optical cavity must be tuned to the preferredfrequency at which light is to be emitted by carefully depositing layersof the required thickness. The light within the cavity will form astanding wave pattern at the desired frequency and with a reduced angleof emission. Optical cavities of this type are known in the art, as aresuitable metallic electrodes, for example silver. See for examplepublished US US Patent application 20030184892 published Oct. 2, 2003,by Lu et al., which is incorporated herein by reference. It is alsopossible to use optical cavity designs that produce coherent laser lightas described in published US patent application No. US20030161368published Aug. 28, 2003 by Kahen et al. and US20020171088 published Nov.21, 2002 by Kahen et al. which are incorporated herein by reference.Applicants have demonstrated both incoherent and coherent OLED lightemission having a reduced angle of emission from the perpendicular thatis suitable for the present invention.

[0022] In a bottom-emitting display, the electrode 18 must be partiallyreflective while the electrode 30 can be totally reflective. In atop-emitter configuration, the electrode 18 is reflective while theelectrode 30 is partially reflective.

[0023] Applicants have demonstrated the use of an optical cavity for theenhancement of light emission from an OLED structure with bothwhite-light emitting materials and for red, green, and bluelight-emitting materials. In all cases, the use of a properly sizedcavity with the use of a thin layer of silver or silver compounds as thepartially reflective electrode and a thicker layer of either silver oraluminum or compounds of aluminum or silver as the reflective electroderesults in greater light emission orthogonal to the electrodes and witha narrower spectrum. Partially transparent electrodes may also consistof a two-layer structure in which a first layer is a transparentconductor and a second layer is a partially reflective mirror.

[0024] In conventional practice, the use of an optical cavity in adisplay application has the significant drawback of a color change asthe display is viewed at angles other than the orthogonal. In thepresent invention, no such disadvantage is seen since only light that isemitted toward the mirror is used and the emitted light is not intendedfor viewing.

[0025] The emitters may be energized sequentially to provide multiplesignals thereby increasing the signal-to-noise ratio of the result andproviding a more detailed map of any touching implement that inhibitsthe transmission of the infrared light. In yet another mode, theemitters are energized simultaneously and the relative amount of lightsensed by the sensors 64 are used to detect a touch. In thisarrangement, the emitters 62 can be a single long emitter with a singlecontrol signal.

[0026] The use of multiple emitters and sensors enables a very robustsensing apparatus. Single-point failures can be overcome and convexshapes can be detected. High-reliability operation is possible bycombining signals from various emitters sensed by various sensors. Theinfrared signal itself may be modulated to overcome background noise ordifferent frequencies of infrared light may be emitted and detected.

[0027] Referring to FIG. 4, the 45 degree mirrors 66 located above theemitters 62 and sensors 64 may be formed by a reflective surface on anenclosure 70 enclosing the integrated display and touchscreen. Referringto FIG. 5, the optics for directing light emitted from the light emitter62 across the display to the light sensor 64 may comprise light pipes72.

[0028] Referring to FIG. 6, a bottom-emitting OLED display device withan integrated optical touch screen according to another embodiment ofthe present invention includes a rectangular substrate 42 with anencapsulating cover 44. Located on the substrate is an OLED display 60including electrodes and multiple layers of materials such ashole-injection layers and electron transport layers as is well known inthe art (not shown). Light 49 emitted from the display passes directlythrough the substrate 42 or is reflected from the encapsulating cover 44and passes through the substrate 42.

[0029] Because the present invention does not require a separate frameor substrate for the touch screen, it reduces the weight, size(thickness), and cost of a combined touch screen and OLED displaydevice.

[0030] The invention has been described in detail with particularreference to certain preferred embodiments thereof, but it will beunderstood that variations and modifications can be effected within thespirit and scope of the invention.

Parts List

[0031]42 substrate

[0032]44 encapsulating cover

[0033]49 emitted light

[0034]60 OLED display

[0035]62 light emitter

[0036]64 light sensor

[0037]66 mirror

[0038]70 enclosure

[0039]72 light pipe

What is claimed is:
 1. An OLED display and touch screen system,comprising: a) a substrate; b) an OLED display including an array ofindividually addressable OLEDs formed on the substrate; and c) a touchscreen including an OLED light emitter formed on the substrate the OLEDlight emitter defining an optical cavity for reducing the angle ofemission of light from the OLED light emitter and a light sensor formedon the substrate across the display from the OLED light emitter, andoptics located around the display above the OLED light emitter and thelight sensor for directing light emitted from the OLED light emitteracross the display to the light sensor.
 2. The OLED display and touchscreen system claimed in claim 1, wherein the OLED light emittercomprise a first electrode; one or more layers of light emitting organicmaterial formed on the first electrode; an electrode formed on the oneor more layers of organic material; and wherein one of the electrodes isreflective and the other is partially reflective and the electrodes arespaced apart a sufficient amount to form an optical cavity in whichlight emitted from the organic material through the partially reflectiveelectrode has a reduced angle of emission;
 3. The OLED display and touchscreen claimed in claim 1, wherein the OLED light emitter is a lineararray of individually addressable OLEDs and the light sensor is a lineararray of light detecting elements.
 4. The OLED display and touch screenclaimed in claim 3, wherein the OLEDs of the OLED light emitter and thelight detecting elements are interspersed in a plurality of lineararrays.
 5. The OLED display and touch screen claimed in claim 1, whereinthe OLED light emitter is a linear OLED and the light sensor is a lineararray of light detecting elements.
 6. The OLED display and touch screenclaimed in claim 1, wherein the OLED display is a top emitting display.7. The OLED display and touch screen claimed in claim 1, wherein theOLED display is a bottom emitting display.
 8. The OLED display and touchscreen claimed in claim 1, wherein the OLED light emitter emits infraredlight.
 9. The OLED display and touch screen claimed in claim 1, whereinthe optics are 45 degree mirrors.
 10. The OLED display and touch screenclaimed in claim 1, further comprising a frame surrounding the OLEDdisplay, and wherein the 45 degree mirrors are supported by the frame.11. The OLED display and touch screen claimed in claim 1, furthercomprising a frame surrounding the OLED display, and wherein the 45degree mirrors are formed on the frame.
 12. The OLED display and touchscreen claimed in claim 1, wherein the optics are fiber optics.
 13. TheOLED display and touch screen claimed in claim 3, further comprisingcontrol electronics for sequentially activating the OLEDs of the OLEDlight emitter.
 14. The OLED display and touch screen claimed in claim 3,further comprising control electronics for simultaneously activating theOLEDs of the OLED light emitter.
 15. The OLED display and touch screenclaimed in claim 1, further comprising control electronics foractivating the OLED light emitter in a predetermined temporal patternand for filtering an output from the light sensor to detect thepredetermined pattern.
 16. The OLED display and touch screen claimed inclaim 1, further comprising a unitary control electronics forcontrolling both the OLED display and the touch screen.
 17. The OLEDdisplay and touch screen claimed in claim 16, wherein the controlelectronics are formed on the substrate.
 18. The OLED display and touchscreen claimed in claim 1, wherein the light sensor is a non-organiclight detecting element.
 19. The OLED display and touch screen claimedin claim 18, wherein the non-organic light-detecting element is asilicon light detecting element.
 20. The OLED display and touch screenclaimed in claim 1, wherein the light sensor is an organic light sensor.21. The OLED display and touch screen claimed in claim 11, including anenclosure for the display wherein the frame is a portion of theenclosure.
 22. The OLED display and touch screen claimed in claim 2,wherein the partially reflective electrode further comprises atransparent conductor and a partially reflective mirror.
 23. The OLEDdisplay and touch screen claimed in claim 2, wherein the first electrodeis reflective, the second electrode is partially reflective, and thedisplay device is a top-emitting display device.
 24. The OLED displayand touch screen claimed in claim 2, wherein the first electrode ispartially reflective, the second electrode is reflective, and thedisplay device is a bottom emitting display device.
 25. The OLED displayand touch screen claimed in claim 2, wherein the light emitted iscoherent.
 26. The OLED display and touch screen claimed in claim 2,wherein the light emitted is incoherent.